We are studying iron- and magnesium-rich clays from hydrothermal sea floor environments around the world to better understand the nature of ancient clays on Mars.

Submarine hydrothermal sites on Earth produce jets of superheated fluids loaded with metals, known as black smokers. Clays formed in these environments are similar to ancient Martian clays.

Ancient clay minerals on the surface of Mars formed billions of years ago, when liquid water was more available. They provide a valuable record of the ancient Martian climate, as well as hydrothermal processes within the planet's crust.

Methods

We are investigating the spectral similarities of clays from Earth and Mars by comparing their infrared spectra .Clays are detected on Mars by spacecraft in orbit that peer down at the surface using infrared cameras. The NASA rover Curiosity is also in search of clays on the surface, and has unexpectedly found some at an early stage in its mission.

We are also comparing the formation temperatures of submarine clays on Earth with those on Mars. This will reveal more about the environment on Mars where the clays formed.

Understanding the environmental conditions that existed during the formation of these materials is central to revealing Mars’s geological and climate history, and the habitability of its past environments.

Results

We have found that iron and magnesium exchange for each other in submarine clays, and that mixed-layer clays of intermediate composition and structure are very abundant on Earth.

Our research suggests that:

mixed-layer clays may be much more common in nature than previously thought, indicating that complex clays may be abundant on Mars

some Martian clays were caught in a state of arrested development, forming in short-lived or otherwise unstable aqueous conditions

some Martian clays formed in hydrothermal conditions that could have been suitable for the formation or sustenance of microbial life.